LOW POSTURAL TONE

By Sally Mackenzie

Low postural tone, or low muscle tone is the term used for muscle tone which is at the lower end of the normal range of muscle tone. High muscle tone is known as spasticity, and very low muscle tone as flaccidity. However within the normal range there is a subtle difficulty which lies at the lower end of the normal range.

Low muscle tone is usually subtle, but it is a part of the minimal neurological dysfunction syndrome. Nobody knows exactly what the cause is but there appears to be a genetic link predominantly in the male line.

A child with low muscle tone will typically do one of two things: Some want to build up tone so they constantly move around, and are sometimes even seen as hyperactive. Others are "couch potatoes" who flop around from couch to couch constantly seeking support. They usually lean against something. They struggle to get dressed especially their buttons and laces. Some children flustuate between hyperactive fidgetting and couch-potatoes.

The difficulties with low muscle tone are usually picked up at school when they are slow, don’t concentrate, fidget constantly, have poor pencil grip with bad handwriting and poor posture at the desk. They tend to press very hard with pencils often breaking nibs. They may rest their head in their hand whilst writing. Their difficulties in hand writing stem from a lack of proximal (near the body) stability in the shoulder joint and trunk. If they do not have stability near their bodies, it is difficult to have mobility away from the body, i.e. cutting and drawing. In an attempt to gain stability, they may hook their feet around the legs of the chair, "fix" their wrist in one position, elevate their shoulders, become tense, or clench their teeth.

Low muscle tone is sometimes noted around the mouth. These are the children who have poor speech development and slur and drool, particularly when they are concentrating hard. Low muscle tone in the eye muscles may cause an inability to squint.

The history of these children may include a floppiness when they were younger, and they not have crawled for long. Crawling is essential for adequate trunk development, shoulder girdle muscles and hand muscles. They often walk earlier than normal because they don't have the trunk stability to crawl comfortably and would rather get up and walk.

The typical posture of these children is winging of the scapulae, a protruding abdomen and increased lumbar curve, hyper extended knees, arms fixed at the waist, a wide standing base with hperextended knees and not being able to sit or stand still. Their ligaments can also be lax in their elbows, and joints of their fingers bending too far out.

The consequences of having low muscle tone are seen particularly when the child starts formal school and the expectations of sitting still for a long time are introduced. Before school the difficulties may be mostly gross motor co-ordination and balance, however at school, their fine motor skills are affected by the lack of stability in the shoulder girdle. They take longer to complete and task, and fatigue more quickly. Thus they often get behind with other learning tasks and subsequently develop delays in perceptual development and other skills. These children are often described as "bull in a china shop" as they are accident prone, clumsy, fall, trip over things, bump into things and drop things more easily than other children.

Low muscle tone is treated by various techniques including Neurodevelopmental therapy. It can be improved by giving the child the skills to cope with it and build up their own muscle tone. The child is taught various exercises according to his or her needs. A therapy session takes an hour, and it begins with stretching exercises, often on the big ball, preparing the body for gross motor activities when a good posture is maintained. Gross motor activities follow, and finally fine motor activities at the end. Therapy can last between 3 - 6 months, when reassessment is then done.

Sally Mackenzie; 51 Wilson Str, Knysna, 6571.
B.Sc.Hons Occupational Therapy (University of Cape Town),
B.Sc.Hons Psychology (University of South Africa),
Sensory Integration Trained (South African Institute of Sensory Integration),
Diploma of Therapeutic Massage (De Villiers Institute)
phone/fax: +27 (0)44-384 1536